FR3061489A1 - SUPPLY STRUCTURE FOR FORKLIFT - Google Patents

Abstract

The invention relates to a power supply structure (4) for a forklift truck (1), comprising at least: a palletizable crate (5); a terminal block (46) electrical connection, integral with the body, adapted to be connected to the carriage for its power supply; at least one fast charge battery (42) housed in said case and connected to said electrical connection terminal block (46); a charger (44) of said at least one battery (42) housed in said case; and a connecting element (48) connected to the charger (44), integral with the box, and adapted to allow an electrical connection between the charger and a power distribution network external to the carriage.

Description

@ Holder (s): COMMISSION FOR ATOMIC ENERGY AND ALTERNATIVE ENERGIES Public establishment.

O Extension request (s):

® Agent (s): CABINET BEAUMONT.

® SUPPLY STRUCTURE FOR LIFT TRUCK.

FR 3,061,489 - A1 (57) The invention relates to a structure (4) for supplying electrical power to a forklift (1), comprising at least: a palletizable box (5); an electrical connection terminal block (46), integral with the body, able to be connected to the carriage for its electrical supply; at least one quick charge battery (42) housed in said body and connected to said terminal block (46) for electrical connection; a charger (44) of said at least one battery (42), housed in said case; and a connection element (48) connected to the charger (44), integral with the body, and capable of allowing an electrical connection between the charger and an electricity distribution network external to the carriage.

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SUPPLY STRUCTURE FOR LIFT TRUCK

Field

The present description relates generally to power systems and, more particularly, the production of an electrical power structure for a forklift. Presentation of the prior art

A forklift needs an energy source. A first category of trucks is equipped with thermal engines. A second category to which this description applies is equipped with a power supply structure consisting of rechargeable batteries.

A traditional electrical supply structure consists of a battery pack comprising lead batteries housed in a handling case and interconnected so as to have only two terminals (positive and negative) for connection of the battery pack either to the electric motor of the cart, or to a battery charger external to the cart. The feeding structure is particularly bulky and heavy.

More recently, forklifts with lithium batteries have been proposed. The batteries are permanently integrated in the trolley which is equipped with a charger intended to be connected to the electricity distribution network. For

B15635 - DD17630ST the user, switching from one solution (lead-acid batteries) to another (lithium batteries) requires replacing the fleet of forklifts, which represents a significant investment which can be dissuasive.

summary

One embodiment provides a power supply structure for a forklift which overcomes all or part of the disadvantages of current structures.

One embodiment offers a solution compatible with forklifts designed to use lead-acid battery packs.

Thus, one embodiment provides a power supply structure for a forklift, comprising at least:

a palletizable box;

an electrical connection terminal block secured to the body, capable of being connected to the trolley for its electrical supply;

at least one quick charge battery housed in said box and connected to said electrical connection terminal block;

a charger for said at least one battery, housed in said case; and a connection element connected to the charger, integral with the body, and able to allow an electrical connection between the charger and an electricity distribution network external to the trolley.

According to one embodiment, said connection element comprises a cable for connecting the charger to the electricity distribution network.

According to one embodiment, the charger comprises a galvanic transformer at the frequency of the electrical network, the transformer participating in weighting the forklift.

According to one embodiment, the box is filled with oil.

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According to one embodiment, the structure comprises at least one energy storage module having two connection terminals, each module comprising a battery and a bidirectional converter, the bidirectional converter being connected on the one hand to the associated battery and elsewhere on the module connection terminals.

According to one embodiment, for each module, the bidirectional converter serves as a DC / DC converter during the charging periods to transfer energy from the network to the module battery, and serves as a DC / DC converter during the charging periods. discharge to transfer energy from the battery to a power supply terminal on the truck.

According to one embodiment, the discharge of the battery assembly is controlled to emulate a discharge of the lead battery or batteries.

One embodiment provides a forklift having a power supply structure.

One embodiment provides a method of transforming the supply structure of a forklift initially comprising a palletizable box filled with slow charge batteries, such as lead batteries, the slow charge batteries being connected to a terminal block. electrical connection integral with the palletizable box, the connection terminal block being connected to an electrical device of the forklift for its electrical supply, the method comprising the following steps:

remove said palletizable box filled with slow-charging batteries, by disconnecting the electrical connection terminal secured to the palletizable box; and

- Insert, in the space previously dedicated to said body, an electrical supply structure according to one of the preceding claims, by connecting the terminal block of said electrical supply structure to the electrical device of the forklift.

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One embodiment provides a method of electrically charging a forklift, comprising the following steps:

- electrically connecting said connection element of the trolley's electrical supply structure to an electricity distribution network; and

- Switching on said charger to transfer electrical energy from the electricity distribution network to said at least one battery.

Brief description of the drawings

These characteristics and advantages, as well as others, will be explained in detail in the following description of particular embodiments made without implied limitation in relation to the attached figures among which:

Figure 1 is a perspective representation of a forklift;

Figure 2 is a perspective representation of a forklift and a conventional battery pack being implemented;

Figure 3 is a schematic perspective view of an embodiment of a lithium battery power supply structure of a forklift;

Figure 4 is a simplified electrical block diagram of the embodiment of Figure 3 and its connection to the motor of the electric carriage;

FIG. 5 illustrates another representation of the electrical diagram of an embodiment of a power supply structure of a forklift; and Figure 6 shows, very schematically, another embodiment of a power supply structure of a forklift.

detailed description

For the sake of clarity, only the elements which are useful for understanding the embodiments described have been shown and will be detailed. In particular, the elements of the

B15635 - DD17630ST forklift, other than its battery power supply structure, has not been detailed, the embodiments described being compatible with the usual forklifts. In addition, the constitution and construction of the systems upstream (electrical network for charging the batteries) and downstream (electric motor) have not been detailed either, the embodiments described here again being compatible with the usual systems. It should be noted that, in the figures, the structural and / or functional elements common to the different embodiments may have the same references and may have identical structural, dimensional and material properties. Unless otherwise specified, the expressions approximately, substantially and in the order of mean to the nearest 10%, preferably to 5%, or to 10 °, preferably to 5 °.

Figure 1 is a perspective representation of a forklift.

Figure 2 is a perspective representation of a forklift and a conventional battery pack being put in place.

A lift truck 1 is made up of a chassis 12, carrying the various equipment (engine, transmission, lifting system 14, seat 16, etc.), and mounted on wheels 18. The chassis 12 also carries a battery pack 2, housed under the seat 16. The seat is articulated on a support 17 capable of pivoting to allow the installation of the battery pack 2 (see Figure 2). The set 22 of lead batteries is housed in a palletizable box 3, in which these batteries are interconnected. Charging the batteries in a standard trolley requires removing the case 3, transporting it to a charging area and charging the battery pack 2.

The use of lead-acid batteries in forklifts has many disadvantages, including:

- the need to have several battery packs per lift truck due to time (more than ten

B15635 - DD17630ST hours) of charge and rest required between two uses of a battery pack;

- the need for a charging room for the battery packs being charged;

- degassing during charging operations;

- handling of particularly heavy and bulky battery packs to charge them and put them back into service on forklifts;

- maintenance operations for lead-acid batteries (notably recharging with water);

- etc.

Forklifts equipped with lithium batteries have already been proposed. The use of lithium batteries has multiple advantages over lead batteries, including:

- less bulk;

- a better lifespan;

- faster charging; and

- absence of degassing.

However, current forklifts equipped with lithium batteries have drawbacks which limit their development. In particular, they must be developed specifically around the use of lithium batteries, which makes them incompatible with existing fleets of forklifts. For example, lead-acid batteries act as a counterweight in forklifts that a lithium battery, lighter for a given capacity, does not fill. Consequently, this generates considerable investments for a company wishing to switch from one technology to another.

The embodiments described below derive from a new analysis of the needs and constraints associated with the use of electric forklifts.

It is planned to take advantage of the current configuration of lead battery power structures to propose

B15635 - DD17630ST a lithium battery power supply structure which can be used in place of existing lead-acid battery cases.

Figure 3 is a schematic perspective view of an embodiment of a structure 4 of lithium battery power supply of a forklift.

Figure 4 is a simplified electrical block diagram of the embodiment of Figure 3 and its connection to the motor of the electric carriage.

FIG. 5 illustrates another representation of the equivalent electrical diagram of an embodiment of a structure 4 for the electrical supply of a forklift.

According to the embodiments described, provision is made to house, in a palletizable box 5, substantially the same size as the boxes 3 of the lead-acid battery packs, at the

minus: - a set 42 of lithium batteries; a charger 44 for the batteries of the set 42, from an alternative source of electrical energy single-phase or three-phase (not shown); - a terminal block 46 for connection of the assembly 42 to the motor (not shown) of the forklift; and an element 48 (socket for receiving a cable or cable fitted with a plug) for connecting the charger 44 to the source of electrical energy.

The box 5 is typically a rectangular parallelepiped enclosure, made of steel, preferably provided with a cover.

The connections of the various elements have been illustrated in dotted lines. Typically, the cable 48 (or alternatively the plug) extends (or is connected) to the charger (link 52), the continuous output of the charger 44 is connected (link 54) to the common terminals of the batteries of the assembly 42 which are also connected to terminal block 4 6 (link 56). In FIGS. 4 and 5, the terminals or conductors are respectively referenced, on the DC supply side.

B15635 - DD17630ST positive with the letter "p" and negative terminals or conductors with the letter "n".

Where appropriate, the links include, in addition to the wires carrying energy (power), wires (not shown) carrying control signals.

In addition, switches and / or control circuits can be inserted on all or part of the links.

In the example of FIG. 4, we assume the presence of a control circuit 62 (CTRL) inserted between a positive terminal 42-p of the battery pack 42 and the motor, or more precisely the input of an inverter 64 (PI) supplying the motor 66 (M). A positive conductor 54-p connects, in this example, the battery assembly 42 to the charger 44 (CHARGER). Negative conductors 54-n and 56-n connect the battery assembly 42 respectively to the inverter 64 and to the charger 44.

In the example of FIG. 5, which is a functional diagram, we consider the case where the battery assembly 42 (BAT) is connected, by means of switches 74, to the conductors 54 and 56. The two conductors 56 -p and 56-n are connected on the one hand to switches 72 constituting the circuit 62 and, on the other hand, to the output of the charger 44.

Preferably, the volume available inside the box 5 is used to ballast the structure. This preserves the counterweight function of conventional battery packs.

According to one embodiment, metal or cast iron weights are provided.

According to another embodiment, all or part of the ballast consists of oil (the body is filled with oil), which contributes to improving the cooling, the oil being a good thermal conductor.

According to another embodiment, the space is occupied by one or more batteries connected in parallel to form the set of batteries 42. This provides a redundancy function in the event that one of the batteries malfunctions. Management

B15635 - DD17630ST of modules or set of redundancy batteries is itself known.

According to another embodiment, the charger 44 includes a galvanic transformer at the frequency of the electrical network (50Hz or 60Hz) rather than a switching converter in order to participate in the ballast. Thus, while the use of this type of transformer is generally seen as a disadvantage due to the weight and the bulk, this disadvantage is here transformed into an advantage.

Integrating the battery pack and the charger into a box 5, compatible with existing forklifts, has many advantages, including:

- Forklift users do not need to change their fleet of forklifts to take advantage of lithium batteries and all the associated advantages, which represents a considerable gain;

- Forklift manufacturers do not need to change their range;

- Recharging operations are simplified. Just plug in the charger without needing to extract the forklift's power structure. The rapid charging of lithium batteries with a charger sized to be quick can lead to charging times of one to a few hours.

FIG. 6 very schematically shows another embodiment of a supply structure 4.

According to this embodiment, the chopper function of the charger is used bidirectionally, that is to say, step-down during charging and step-up during discharge or vice versa.

In the example shown, a three-phase supply voltage is assumed. The charger 44 then comprises, inter alia:

B15635 - DD17630ST

- a transformer 441 receiving a three-phase alternating voltage and supplying an alternating voltage Vac;

- a rectifier bridge 443 of the Vac voltage, providing a rectified voltage; and

- a chopper 8 operating as a DC / DC converter to charge the battery pack 42.

The chopper 8 is shown diagrammatically in the form of two switches 81 and 82 in series between the output terminals 445 and 447 of the rectifier 443, each switch 81, 82 being in parallel with a diode 83, respectively 84. The midpoint 85 of l the series association of the switches 81 and 82 is connected, by means of an inductive element 86, to a terminal, for example positive 42-p, of the battery assembly 42. The terminal 447 is common to the terminal negative 42-n of the battery pack 42. The anodes of the diodes 83 and 84 are respectively connected to the terminals 85 and 42-n.

The output of rectifier 443 is also connected to the control circuit 62 (the conductors 56-p and 56-n are respectively connected to terminals 445 and 447).

In such an embodiment, the chopper 8 serves not only as a DC / DC converter during the charging phases, but also as a DC / DC converter during the discharging phases.

One can take advantage of the separation of the converter 8 and the other elements of the charger to provide several batteries, each associated with a converter 8. It is thus possible to have several energy storage modules MS-1 to MS-n, each module of MS-i storage including a BAT-i battery and an 8-i converter. Thus, for each MS-i module, the bidirectional chopper 8-i is adapted on the one hand to the voltage of the associated BAT-i battery, for example 12 or 24 volts and on the other hand to the common voltage applied between the terminals 445 and 447, for example 24V, 48V and 80V.

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This makes it possible to standardize the manufacture of an MS storage module by providing a “generic” bidirectional chopper capable of adapting to different types of battery, in particular with several battery voltages, and capable of adapting to different voltage levels. to be supplied to adapt in particular to the three usual voltages of forklifts, namely 24V, 48V and 80V. The modules MS-1 to MS-n can thus be associated in parallel. In particular, it will be possible to use a single type of module to adapt to the three usual voltages of forklifts, namely 24V, 48V and 80V.

This modular embodiment also has the advantage of ensuring redundancy of the batteries and of the DC / DC converter part, a faulty module which can easily be compensated for by the other non-faulty modules. Furthermore, conventionally, for each module, safety elements (not shown) of fuse type F can be provided between the chopper 8 and the battery assembly 42 and / or between the chopper and the terminal 445.

Since the transformer and rectifier are elements that are unlikely to fail, they can advantageously be common to all the modules.

Another advantage of using a bidirectional chopper (whether in a modular embodiment or not) is that the continuous / continuous conversion in period of use of the forklift makes it possible to emulate and restore the operation of a lead acid battery. Indeed, we know the evolution of the voltage as a function of the state of charge (SoC) for a lead battery and for a lithium battery. The setpoint of the chopper can be adapted as a function of the state of charge measured at the terminals of the battery assembly 42 (such a measurement is in itself usual) of the module and of a table of correspondence between a state of charge equivalent of a lead battery and that of a lithium battery.

In the case described above of using a set of modules MS-1 to MS-n in parallel, it will be possible to carry out

B15635 - DD17630ST a measurement of all the SoC charge states of the different batteries BAT-1 to BAT-n and estimate an average charge state, SoC-average, to determine the voltage setpoint to be applied between terminals 445 and 447 , each bidirectional chopper 8-i receiving this voltage setpoint.

An advantage of the embodiments which have been described is that it is now possible to keep a fleet of forklifts while benefiting from lithium batteries.

Another advantage is that the change from a lead structure to a lithium structure is particularly simple. It suffices to remove the lead-acid battery case and to replace case 5 of the lithium battery structure.

Another advantage is that the transformation is reversible. Indeed, we go from a lead battery supply structure to a lithium battery supply structure and vice versa, simply by changing the body. Consequently, this facilitates the management of large parks and a gradual change of structures.

The embodiments described above indicate that the batteries used are lithium batteries. However, other types of batteries having similar properties can be used, for example batteries based on Sodium-Ion. In order to be able to present the aforementioned advantages and be interesting in the context of a replacement process (“retrofit” in English), the batteries must be able to be charged quickly, in one hour or even two hours. By rapid charge is meant batteries capable of being recharged at least 2 times faster, or even 5 or 10 times faster than so-called slow charge batteries such as lead batteries. In addition, it is necessary that the batteries can be partially recharged, during a forklift break, regardless of their initial state of charge before partial charge.

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In addition, the term "palletizable" should be understood to mean "capable of being handled with a means of handling". Once the new box (with fast-charging batteries) installed, it is possible that it will be mechanically locked for its correct maintenance on the lift truck. Such a locked box after installation is of course within the scope of the present invention although it is not immediately manipulable.

In addition, the batteries used in the examples described can, conventionally, be made up of several elementary electrochemical cells placed in series and / or parallel.

In addition, the charger 44 is in practice controlled by a control device not shown, which will control the starting of the charger when the connection element 48 is connected to the electrical distribution network. Preferably, the starting of the charger 44 will be accompanied by an opening of the control circuit (CTRL) 62, in particular to avoid any risk of undesirable starting of the carriage resulting in disconnection or untimely damage of the connection element. .

Various embodiments and variants have been described. Certain embodiments and variants may be combined and other variants and modifications will appear to those skilled in the art. In particular, the choice between the different embodiments and variants depends on the application. In addition, the practical implementation of the embodiments and variants which have been described is within the reach of those skilled in the art from the functional indications given above. In particular, the commands of the switches and circuits are within the reach of those skilled in the art from the usual commands of lead or lithium battery chargers and their charging and discharging systems.

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Claims (10)

1. Structure (4) of electrical supply for forklift (1), comprising at least: a palletizable box (5); an electrical connection terminal block (46), integral with the body, able to be connected to the carriage for its electrical supply; at least one quick charge battery (42) housed in said body and connected to said terminal block (46) for electrical connection; a charger (44) of said at least one battery (42), housed in said case; and a connection element (48) connected to the charger (44), integral with the body, and capable of allowing an electrical connection between the charger and an electricity distribution network external to the carriage. 2. Structure according to claim 1, wherein said connecting element (48) comprises a cable (48) for connecting the charger (44) to the electricity distribution network. 3. Structure according to any one of claims 1 to 2, wherein the charger (44) comprises a galvanic transformer (441) at the frequency of the electrical network, the transformer participating in weighting the forklift (1). 4. Structure according to any one of claims 1 to 3, wherein the box (5) is filled with oil. 5. Structure according to any one of claims 1 to 4, comprising at least one energy storage module having two connection terminals, each module comprising a battery and a bidirectional converter (8), the bidirectional converter being connected to on the one hand to the associated battery and on the other hand to the module connection terminals. 6. Structure according to claim 5, in which for each module, the bidirectional converter (8) serves as a DC / DC converter during the charging periods for Β15635 - DD17630ST transfer energy from the network to the battery of the module, and serves as a DC / DC converter during discharge periods to transfer energy from the battery to a terminal block for the truck's power supply. 7. Structure according to 1 ¹ any one of claims 1 to 6, wherein the discharge of the battery pack (42) is controlled to emulate a discharge of the lead or batteries. 8. Forklift (1) comprising an electrical supply structure (4) according to any one of claims 1 to 7. 9. Method for transforming the supply structure of a forklift truck initially comprising a palletizable box filled with slow charge batteries, such as lead batteries, the slow charge batteries being connected to an electrical connection terminal block integral with the palletizable box, the connection terminal being connected to a following supply device: electric of the electric forklift, the method comprising for its battery steps to remove said palletizable box by disconnecting the filled slow charge terminal, electric secured to the palletizable box; insert, in the location previously dedicated to said body, an electrical supply structure according to one of the connections of any of claims 1 to 7, by connecting the terminal block of said electrical supply structure to the electrical device of the forklift. 10. A method of electrically charging a forklift truck according to claim 8, comprising the following steps: - electrically connecting said connection element of the trolley's electrical supply structure to an electricity distribution network; and B15635 - DD17630ST - Switching on said charger to transfer electrical energy from the electricity distribution network to said at least one battery. B 15635 DD17630 1/3